JPH10119055A - Manufacture of resin hollow article and lost core used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the favorable gas barrier properties of a resin hollow article by a method wherein a lost core, on which accessory parts are set, is wrapped with a gas barrier sheet and, after being formed with a resin matrix layer on the core in molds, taken out of the molds for allowing the core to be lost. SOLUTION: Accessory parts 6 are set on a porous lost core 4. The resultant lost core 4 is wrapped in a gas barrier sheet and then arranged between an upper mold 5 and a lower mold 7. Outside the sheet, a resin matrix layer 8 is formed, while a resin member having the core 4 inside is formed. After the resin member having the core 4 inside is taken out of the molds, the core 4 is lost through its liquefication or gasification so as to obtain a resin hollow article having the accessory parts 6 integrally. The sheet sealed hermetically wrapped the core is stuck onto the outside of the core 4, to which the sheet is set, by vacuumizing the interior of the sheet. Further, the matrix layer 8 is formed by injecting a molten resin in a cavity between the core 4 and the molds 5 and 7 and then solidifying the injected resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a hollow resin article and a fugitive core used for the method.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 7-304057 discloses a method in which a fugitive core is set in a mold, a molten resin is injected into a cavity between the core and the mold, and after the molten resin solidifies, the fugitive core is set. Is disclosed to obtain a hollow resin product. If it is necessary to attach an accessory such as a cut-off valve to a resin container on which a gas barrier layer is formed, such as a vehicle fuel container (fuel tank), a mounting hole larger than the accessory is conventionally provided in the resin container. Opening, attachment parts are attached there, and the airtightness is maintained by bonding or the like, and they are integrated.

[0003]

However, in the conventional structure, since the gas barrier layer is perforated to attach the accessory parts to the resin container, skills are required to secure the gas permeation prevention performance, and the manufacturing cost is reduced. Will be higher. Also, if you try to attach accessories without drilling holes in the resin container,
During the production of the resin container, it is necessary to divide the resin container into two parts, attach the accessory parts to the resin container from the inner surface side, and then weld the divided parts, and the leakage resistance and reliability of the welded part become problems. An object of the present invention is to eliminate the necessity of making a hole in a hollow resin article and integrally welding the hollow resin article into a two-part structure in order to integrally attach the accessory parts. Therefore, gas permeation prevention (gas barrier properties) is not required. It is an object of the present invention to provide a method for producing a hollow resin article and a core used therefor, which ensure the above.

[0004]

The present invention to achieve the above object is as follows. (1) The accessory components are set on the fugitive core, and the fugitive core on which the accessory components are set is wrapped together with a gas barrier sheet from the outside together with the accessory components. Placed in a mold, forming a resin base material layer on the outside of the sheet, forming a resin member having the fugitive core on the inside, and forming the resin member having the fugitive core on the inside of the mold. And removing the extinguisher core from the core to obtain a hollow resin article integrally having the accessory parts. (2) The accessory parts are set on the fugitive core, the fugitive core on which the accessory parts are set is arranged in a mold, and a resin base material layer is provided outside the fugitive core on which the accessory parts are set. Forming and forming a resin member having the fugitive core on the inside, removing the resin member having the fugitive core on the inside from the mold, and then dissipating the fugitive core to remove the accessory part. A method for producing a hollow resin article comprising the steps of obtaining a hollow resin article having the same. (3) Using the fugitive core to produce a resin hollow article integrally having attached parts and having a gas barrier sheet having welding burrs attached to a surface contacting the fugitive core. A method for producing a hollow resin article, which is a fugitive core used in a method for producing a hollow resin article, wherein a storage portion for accommodating the welding flash of the sheet is formed at a core portion in contact with the welding flash of the sheet. Efficient core used.

In the method (1) for producing a hollow resin article,
After using the core that was settled and attaching accessory parts to it, wrapping it in a sheet, forming a resin base material layer, and then letting the core disappear, so attaching the accessory parts It is not necessary to make a hole in the resin base material layer, and it is not necessary to divide the hollow product into two parts and insert and attach the accessory parts inside the hollow product. Therefore, the gas barrier property of the hollow resin article manufactured by this method is high. The method for manufacturing a hollow resin article of the above (2) is a case of a resin container having no gas barrier layer, but has an action similar to that of the above (1). There is no need to make a hole, and it is not necessary to divide the hollow resin article into two parts and insert and attach the accessory parts inside the hollow article. Since the vanishable core of the above (3) has a storage portion for storing the welding burrs of the sheet, the thickness of the resin base material layer does not become thin even at the welding burrs of the sheet, and the strength of the hollow resin product is secured. You.

[0006]

FIG. 1 shows a hollow resin article manufactured by a method for manufacturing a hollow resin article (for example, an automobile fuel tank) according to an embodiment of the present invention, and FIGS. 3 shows a method for producing a hollow resin article. As shown in FIG. 1, the resin hollow article 13 has a resin container (resin tank) integrally attached with an accessory 6 made of metal or resin. When the resin hollow article 13 is an automobile fuel tank, as shown in FIGS. 2, 6, 11, and 12, the cutoff valve 6, the pipe 9, the sub tank 10, the separator 1
1 and the like are integrally attached to the resin tank (including those integrally formed). Usually, the cut-off valve 6 and the pipe 9 are made of metal, and the sub-tank 1
0, the separator 11 is made of resin. The cutoff valve 6 is a valve for bleeding air accumulated in the upper portion of the fuel tank when fuel is supplied to the fuel tank through the inlet pipe 9. The cutoff valve 6 closes when the fuel rises to the valve position, and the liquid level becomes lower. It is a valve that opens when it is below.

When the resin hollow article 13 is a fuel tank for an automobile, usually, as shown in FIGS. 4 and 7, a multilayer sheet (multilayer film) 1 is attached to the inner surface of the resin tank to improve gas barrier properties. You. The multilayer sheet 1 has a structure in which a gas barrier layer 1a is sandwiched between resin layers 1b of the same kind as the resin of the base material 8. The gas barrier layer 1a is also called a gas-permeable layer, and is made of an ethylene vinyl alcohol (EVOH) layer or a nylon (registered trademark) layer. The resin layer 1b is made of a high-density polyethylene (HDPE) layer of the same type as the base resin (eg, polyethylene resin). As a multilayer sheet 1 having this structure, there is, for example, Diamilon MF (registered trademark) manufactured by Mitsubishi Plastics Corporation. Also, as HDPE,
There is F6040V (registered trademark) manufactured by Japan Polyolefin Co., Ltd. The gas barrier layer 1a improves the gas permeation resistance of the multilayer sheet 1, and the resin layer 1b enhances the multilayer sheet 1.
And the base material (the same high-density polyethylene as the HDPE layer of the sheet 1 or a similar resin) 8 is improved. That is, the surface of the HDPE layer of the sheet 1 is melted or semi-melted by the heat of the molten resin of the base material 8 at the time of injection, thereby improving the integrity with the base material 8 layer.

The method for manufacturing a hollow resin article (for example, a fuel tank for an automobile) according to the embodiment of the present invention comprises the steps of setting an accessory 6 on a porous vanishable core (lost core) 4 as shown in FIG. As shown in FIG. 3, the vanishable core 4 on which the accessory 6 is set is attached to the sheet 1 together with the accessory 6 from the outside.
5, a step of disposing the core 4 wrapped by the sheet 1 as shown in FIG. 5 in a mold (for example, a mold composed of an upper mold 5 and a lower mold 7), and as shown in FIG. A step of forming an eight-layer resin base material on the outside of the sheet 1 to form a resin member having a fugitive core 4 on the inside, and a step of forming a resin member having a fugitive core 4 on the inside as shown in FIG. It comprises a step of removing the mold from the mold (demolding step), and then a step of removing the eliminable core 4 (removing it by liquefaction or vaporization) to obtain a resin hollow article integrally having the accessory 6.

In the above manufacturing method, the sheet 1 is a sheet 1 having a gas barrier property (for example, a multilayer sheet 1 having a gas barrier layer 1a). When wrapping the vanishable core 4 in the sheet 1, as shown in FIGS.
The upper and lower sheets 1 are wrapped from above and below by sandwiching the core 4 from above and below with the outer edge of the sheet sandwiched between the hot plate 2 and the holding plate 3, and the hot plate 2 is heated (electrically heated) in this state. Are fused (heat-sealed). The vanishable core 4 is made of a porous core, and the inside of the sheet 1 is decompressed (evacuated) in a state where the vanishable core is wrapped and sealed by the sheet 1, and the vanishable core 4 is a porous core. Utilizing the fact, the sheet 1 is adsorbed to the outer surface of the core 4 on which the accessory 6 is set, and the shape is brought into close contact with the outer surface of the core 4 on which the accessory 6 is set.

In the step of forming the base material 8 layer on the outside of the sheet 1, cavities are formed between the vanishable core 8 and the molds 5 and 7 as shown in the illustrated example, and molten resin is injected into the cavities. And then solidify to form a base material layer, or by other methods, for example, a sheet flow stamping method in which a heated base material resin sheet is placed on the multilayer sheet 1 and hot stamped by a press, or a molten resin is pressed. The base material layer may be formed by hot flow stamping.
In addition to the cutoff valve, the accessory 6
5 or 6, a slit is formed in the core 4 and the molten resin is poured into the slit and solidified when the molten resin is injected, as shown in FIGS. The sub-tank 10 and the separator 11 may be used.

When the upper and lower sheets 1 in FIG. 3 are thermally fused, a fusion burr 12 may be formed in the fusion portion as shown in FIG. 8, and the thickness of the base material layer 8 is reduced. May be 12 minutes thinner. In order to prevent this, in the fugitive core 4, a burr having a depth enough to accommodate the burr 12 as shown in FIGS. A storage section (burr storage recess) 14 is formed in advance. Using the flow of the molten metal at the time of molten metal injection,
As shown in FIG. 9 and FIG.
And push it inside. Thereby, the fusion burr 12
In this case, the thickness of the base material layer 8 is prevented from being reduced,
The strength of the base material layer 8 is ensured.

Although the above embodiment is a method for manufacturing a hollow resin article 13 having the sheet 1 on the inner surface, the hollow resin article 13 may not have the sheet 1. The method for manufacturing the hollow resin article 13 without the sheet 1 includes a step of setting the accessory 6 on the fugitive core 4 as shown in FIG. 2 and a step of setting the accessory 6 as shown in FIG. Disposing the fugitive core 4 in the molds 5 and 7; forming an eight-layer resin base material on the outer side of the fugitive core 4 on which the accessory 6 is set; and having the fugitive core 4 inside. A step of forming a resin member, and removing the resin member 8 having the eliminable core 4 inside from the molds 5 and 7, and then erasing the eliminable core 4 to form a resin hollow article integrally having the accessory 6. And a step of obtaining.

Next, the operation will be described. In the method for producing a hollow resin article having the sheet 1 in the embodiment of the present invention,
Since the vanishable core 4 on which the accessory parts 6 are set is wrapped from the outside together with the accessory parts 6, it is not necessary to make the hollow resin article into a two-part structure when attaching the accessory parts 6, and the base material layer 8
Further, it is not necessary to make a hole in the sheet 1, and it is not necessary to seal the hole when there is a hole. Further, since the sheet 1 is heat-sealed at the mating portion, the sealing property of the mating portion is good. As a result, the gas permeation resistance of the hollow resin article 13 wrapped with the sheet 1 having the barrier layer 1a is high. Therefore, the present method can be used for manufacturing a container in which gas permeation is not allowed or is not desirable, such as a fuel tank, and can exert a large gas permeation resistance effect and a leakage prevention effect.

Since the core is wrapped in the hollow resin article 13, it is impossible to remove the core with a normal metal core. However, in this method, the core is an extinguisher core. Can be removed by dissolving or vaporizing the dissipative core even after it is wrapped in the hollow resin article 13. Such a fugitive core is made of a resin having a melting point lower than that of the base resin 8 and is then heated and melted and removed while the base resin is not melted, or the fugitive core is made of a polyacetal resin. In the removal step, nitric acid is removed from the resin hollow article 13 by a chemical reaction in a chemical reaction furnace in which the nitric acid is vaporized and decomposed into a gas phase.

In the case of the hollow resin article 13 having the sheet 1, the burrs 12 may be formed at the sheet welding portion. The thickness of the material layer 8 can be secured, and the strength of the hollow resin article 13 can be secured.

Even in the case of the hollow resin article 13 without the sheet 1, the same operation as the above-mentioned operation is obtained with respect to the operation of parts other than the sheet. That is, since the accessory base 6 is formed on the vanishable core 4 and eight layers of the resin base material are formed from the outside, when attaching the accessory 6, two resin hollow articles are required.
There is no need for a split structure. Since there is no need to make a hole in the eight layers of the resin base material when attaching the accessory part 6 and there is no need to divide the resin base material into two layers, the sealing property is good. Further, even if the core is wrapped from the outside with the base material 8, the core can be eliminated and removed because the core is composed of the vanishing core.

[0017]

According to the method for manufacturing a hollow resin article according to the first aspect, a resin core material layer is formed by using a fugitive core, setting an accessory on the core, wrapping the accessory in a sheet, and wrapping the accessory. And
Since the core was then removed, there was no need to drill holes in the resin base material layer and sheet to attach the accessory, and it was necessary to divide the hollow product into two parts and insert the accessory into the hollow product. Nor. Therefore, the gas barrier property of the hollow resin article becomes extremely good. The method for manufacturing a hollow resin article according to claim 2 is a case of a resin container having no gas barrier layer, but has an effect similar to the effect of claim 1,
It is not necessary to make a hole in the resin base material layer to attach the accessory, and it is not necessary to divide the hollow article into two parts and insert and attach the accessory inside the hollow article. According to the fugitive core of claim 3, since the fugitive core has a storage portion for storing the welding burr of the sheet, the thickness of the resin base material layer does not become thin even at the fusing burr portion of the sheet, and the resin hollow product has Strength is ensured.

[Brief description of the drawings]

FIG. 1 is a perspective view of a fuel tank manufactured by a method for manufacturing a hollow resin article according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view of the method for manufacturing a hollow resin article according to the embodiment of the present invention, in which the accessory is set on a fugitive core;
It is sectional drawing corresponding to -X-ray.

FIG. 3 is a cross-sectional view of a method for manufacturing a hollow resin article according to an embodiment of the present invention, in which a vanishable core to which accessories are set is wrapped in a sheet.

FIG. 4 is a partially enlarged sectional view of a sheet.

FIG. 5 is a cross-sectional view showing a state in which a core is set in a mold in the method for manufacturing a hollow resin article according to the embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a state in which a base resin layer is formed between a core and a mold in the method for manufacturing a hollow resin article according to the embodiment of the present invention.

FIG. 7 is a partially enlarged cross-sectional view of a base resin and a sheet in a portion A of FIG. 6;

FIG. 8 is a partially enlarged cross-sectional view of a portion B of FIG. 6 of the core which is used in the method of manufacturing a hollow resin article according to the embodiment of the present invention.

FIG. 9 is a partially enlarged cross-sectional view of the vanishable core in a state where the molten resin has flowed further than the state of FIG. 8;

FIG. 10 is a partially enlarged cross-sectional view of the vanishable core in a state where the molten resin has flowed further than the state in FIG. 9;

FIG. 11 is an enlarged sectional view of an accessory part (cutoff valve) of the hollow resin article manufactured by the method for manufacturing a hollow resin article according to the embodiment of the present invention.

FIG. 12 is an enlarged sectional view of an accessory part (pipe) of the hollow resin article manufactured by the method for manufacturing a hollow resin article according to the embodiment of the present invention.

FIG. 13 is a cross-sectional view illustrating a state in which the hollow resin article is removed from the mold in the method for manufacturing a hollow resin article according to the embodiment of the present invention.

FIG. 14 is a cross-sectional view showing a state in which a fugitive core has been removed from a hollow resin article in the method for producing a hollow resin article according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 (Multilayer) sheet 1a Gas barrier layer 2 Hot plate 3 Holding plate 4 Evaporable core 5 Upper die 6 Auxiliary parts (cutoff valve) 7 Lower die 8 Base material layer 9 Auxiliary parts (pipe) 10 Auxiliary parts (sub tank) 11 Accessories (separator) 12 Welding burr 13 Hollow resin product 14 Burr storage

Claims (3)

[Claims] 1. An accessory component is set on a vanishable core, the vanishable core on which the accessory component is set is wrapped together with a gas barrier sheet from the outside together with the accessory component, and the vanishing core wrapped by the sheet is provided. Placing a child in a mold, forming a resin base material layer on the outside of the sheet to form a resin member having the vanishable core inside, and forming the resin member having the vanishable core inside. A method for producing a hollow resin article, comprising the steps of: removing the dissipative core after removing the core from the mold to obtain a hollow resin article integrally having the accessory parts. 2. An accessory component is set on a fugitive core, the fugitive core on which the accessory component is set is arranged in a mold, and a resin base material is provided outside the fugitive core on which the accessory component is set. Forming a layer to form a resin member having the fugitive core on the inside, removing the resin member having the fugitive core from the mold on the inside, and then dissipating the fugitive core to remove the resin component; A method for producing a hollow resin article comprising the steps of obtaining a hollow resin article integrally having components. 3. A hollow resin article integrally having accessory parts, wherein a sheet having a gas barrier property having welding burrs is adhered to a surface contacting the vanishable core using the vanishable core. Manufacture of a fugitive core for use in a method for manufacturing a hollow resin article to be manufactured, wherein a storage portion for housing the welding flash of the sheet is formed at a core portion in contact with the welding flash of the sheet. Core for use in the method.